1. Field of the Invention
The present invention provides a display and a method for producing the same. In particular, the present invention provides an optical film for use in a display and a method for producing the same.
2. Descriptions of the Related Art
Current liquid crystal displays (LCDs) generally have brightness enhancement films (BEFs), which improve the brightness and light emitting efficiency of the LCDs. Conventional BEFs rely on backlight modules as the light source, and works under the following principle: an additional reflective optical film is added to the conventional backlight module, so that a portion of the light emitted from the backlight module may be recycled by being reflected twice, thus utilizing the light from the backlight module more efficiently. BEFs commonly include prism type BEFs, reflective type polarizing BEFs, and cholesteric liquid crystal reflective BEFs. For example, in a prism type BEF, diffused light is transmitted through the BEF within a range of 70° from the normal by means of refraction and total internal reflection, while the portion of light outside of this range is reflected and retransmitted through the BEF for use. In this way, the brightness of a display may be improved by about 40% to 70%.
In more detail, FIG. 1 illustrates the schematic structure of a conventional display incorporating a reflective type polarizing BEF. The display depicted in FIG. 1 comprises an upper polarizer 101, a lower polarizer 102, a liquid crystal unit 103, a backlight module 104 and a reflective type polarizing BEF 105. The left view of FIG. 1 illustrates a display without the use of a reflective type polarizing BEF, in which case only about 50% of polarized light 106 emitted from the backlight module 104 will be transmitted through the lower polarizer 102 to be used by the liquid crystal unit 103. In comparison, when the reflective type polarizing BEF 105 is incorporated in a display, 50% of the light (indicated as the first polarized light 107) is allowed to be transmitted through the reflective type polarizing BEF 105, while the other 50% of the light (indicated as the second polarized light 108) is reflected. The reflected second polarized light 108 is then reflected a second time for transformation into a polarized light parallel with the first polarized light 107. At this time, the light is transmitted through the lower polarizer 102 and into the liquid crystal unit 103. With the repeated reflection, the brightness of the display is enhanced.
Although the reflective type polarizing BEF technology described above may enhance the brightness of a display, there is a complex structure and manufacturing process. For example, such a film can only be interposed between the backlight module and polarizer. To mitigate optical interference, a diffusing layer has to be used in combination. Furthermore, there is a thickness of more than hundreds of micrometers, which prevents the apparatus from becoming more lightweight and miniaturized. In view of this, it is highly desirable in the art to improve the BEF technologies for use in display panels to simplify the manufacturing process and improve light emitting efficiency.